The present invention relates generally to pressurized, plastic beverage containers and, more particularly, to a closure assembly therefor.
Recently, a pressurized beverage dispensing container known in the industry as a "party ball" has been commercialized in the United States. This beverage dispensing container comprises a generally spherically-shaped container constructed from PET plastic which has a fluid capacity of approximately 5.16 gallons. The container has a single opening at an upper end portion thereof which is sealingly covered with a cap. The cap has a gasket associated therewith which is adapted to be resealingly penetrated at two different regions during the insertion of a pressurization conduit and a beverage discharge conduit.
A prior art closure assembly 11 for such a pressurized, plastic beverage container 13 is illustrated in FIG. 1. The beverage container 13 comprises an upper cylindrical end opening 15 circumscribed by an annular neck 17. The annular neck comprises a top radially extending surface 19 which typically has an outer diameter of approximately 2.23 inches and an inner diameter of 1.960 inches. The annular neck 17 further comprises an axially extending outer surface 21 which is integrally connected to a inwardly and downwardly sloping surface 23 which slopes approximately 30.degree. from a vertical plane and which has a length of approximately 0.055 inch. A radially extending lower surface 25, typically having a length of approximately 0.034 inch, is integrally connected to sloping surface 23 by a shoulder surface which may have a radius of about 0.010 inch. An outwardly and downwardly extending surface 27 is connected to surface 25 through a 0.015-inch-radius surface 27. Surface 27 has a approximately 10.degree. with respect to a vertical plane. Surface 27 is connected to an axially extending surface 29. Axially extending surface 29 terminates at a flange portion 31 which has an outer diameter of approximately 2.625 inches.
A cap 35 which is adapted to be crimpingly attached to neck 17 to seal the opening 15 comprises a flat, radially extending portion 37 and an annular flange portion 39. Cap 35 has a gasket 33 positioned on the interior side thereof which sealingly engages the top surface 19 of the neck 17. The cap flange portion 39 may have a total surface length, measured perpendicular to its direction of annular extension, of approximately 0.373 inch. Flange portion 39 comprises an axially extending portion 41, a radially inwardly and downwardly extending portion 43, and an outwardly concave, arcuate portion 45. During installation of the cap 35, a crimper tool (not shown) urges portion 43 into abutting contact with inwardly and downwardly sloping surface 23 of the annular neck.
The axial force which tends to remove cap 35 after container 13 is pressurized is resisted through the coaction of neck surface 23 and flange diagonal portion 43. Due to the fact that neck 17 is constructed from PET plastic, there is a tendency for neck 17 to flex or creep inwardly 37 due to the continuous force applied thereto by cap flange portion 43. This condition becomes especially pronounced at elevated temperatures. Such inward deflection of neck 17 may cause loss of the seal between cap gasket assembly 35, 33 and neck 17.